IC wafer for identification of circuit dies after dicing

ABSTRACT

Aspects of the present disclosure provide an integrated circuit (IC) wafer having a plurality of circuit dies each bounded by a set of scribe lines. The IC structure includes: a plurality of reference features each respectively positioned in a first layer of one of the plurality of circuit dies. The reference feature of each circuit die is equidistant from a respective set of scribe lines for the circuit die, and a plurality of identification features each positioned in a second layer of one of the plurality of circuit dies. The reference feature of each circuit die has a distinct offset vector indicative of a positional difference between the identification feature for the circuit die and the reference feature for the circuit die, relative to the identification feature of each other circuit die.

BACKGROUND

The subject matter disclosed herein relates to integrated circuit (IC)wafer structures and methods for identifying the location of aparticular die after dicing of the wafer. More specifically, aspects ofthe invention relate to structures which include identification featuresfor indicating the original location of a circuit die on an IC wafer,methods of forming such features, and methods of using such features.

Integrated circuit manufacturing includes fabricating the structure ofmultiple circuit dies together on a single semiconductor wafer. Afterforming one semiconductor wafer, the wafer may be split into multiplecircuit dies. Wafer dicing refers to the process of dicing (i.e.,splitting) the single semiconductor wafer into a plurality of circuitdies for conversion into end products. The dicing of a wafer includesdefining a set of scribe lines, alternatively known as kerf lines, forseparating various regions of the wafer, such that each region includesthe structure of a particular die bounded by a corresponding set ofscribe lines. The dicing process may include the mechanical splitting ofthe wafer, e.g., by laser cutting and/or other procedures for separatingsemiconductor material and elements formed therein into smaller pieces.

One underlying characteristic of wafer dicing is the loss of materialsincluded at or near the set of scribe lines. These materials and regionsmay be known as the IC wafer's kerf region. Conventional testing methodsmay include forming various structures, features, etc., in the kerfregion of an IC wafer to determine the quality of a wafer before it isdiced. IC wafers that pass this stage of testing will then be diced, andthe test structures included in the kerf regions of the wafer will beremoved or otherwise disconnected from functional components of theindividual circuit dies. Pre-dice testing of an IC wafer may not fullyaccount for post-deployment characteristics of a particular product,e.g., functional failures of a fabricated unit. After a wafer is diced,the various wafer dies may be intermixed and/or distributed to differentcustomers or sites without regard to which wafer, or portion of a wafer,may have been used to produce each circuit die. Conventional testing maybe limited to evaluating the characteristics of the entire wafer priorto dicing, or examination of particular units after manufacture, withoutany ability to associate an end product or batch of products with aparticular portion of the original wafer.

SUMMARY

A first aspect of the present disclosure provides an integrated circuit(IC) wafer having a plurality of circuit dies each bounded by a set ofscribe lines, the IC structure including: a plurality of referencefeatures each respectively positioned in a first layer of one of theplurality of circuit dies, wherein the reference feature of each circuitdie is equidistant from a respective set of scribe lines for the circuitdie, and a plurality of identification features each positioned in asecond layer of one of the plurality of circuit dies, the referencefeature of each circuit die having a distinct offset vector indicativeof a positional difference between the identification feature for thecircuit die and the reference feature for the circuit die, relative tothe identification feature of each other circuit die.

A second aspect of the present disclosure provides a method formanufacturing integrated circuit (IC) structures, the method including:forming a plurality of circuit dies in an IC wafer, each of theplurality of circuit dies being bounded by a set of scribe lines,wherein forming the plurality of circuit dies further includes: forminga reference feature in a first layer of each of the plurality of circuitdies, wherein the reference feature of each circuit die is equidistantfrom a respective set of scribe lines for the circuit die, and formingan identification feature in a second layer of each of the plurality ofcircuit dies, the identification feature having an offset vectorindicative of a positional difference between the identification featurefor the circuit die and the reference feature for the circuit die,wherein each of the plurality of circuit dies in the IC wafer includes adistinct offset vector for the identification feature relative to theidentification feature of each other circuit die.

A third aspect of the present disclosure provides a method foridentifying circuit dies, the method including: selecting one of aplurality of circuit dies for analysis, the plurality of circuit diesbeing diced from an IC wafer; measuring an offset vector between anidentification feature of a first layer in the selected circuit die anda reference feature of a second layer in the selected circuit die,wherein each of the plurality of circuit dies includes the referencefeature at a same location, and wherein each of the plurality of circuitdies includes a distinct offset vector indicative of a positionaldifference between the identification feature and the reference featurefor one of the plurality of circuit dies, relative to the identificationfeature of each other circuit die; comparing the measured offset vectorfor the selected circuit die with an index of offset vectors for the ICwafer; and identifying a location of the selected circuit die in theplurality of circuit dies of the IC wafer, based on the comparing of themeasured offset vector with the index of offset vectors for the ICwafer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various embodiments of the invention, in which:

FIG. 1 provides a plan view in plane X-Y of an integrated circuit (IC)wafer and circuit dies according to embodiments of the disclosure.

FIG. 2 provides a plan view in plane X-Y of the IC wafer and magnifiedviews of three circuit dies according to embodiments of the disclosure.

FIG. 3 provides a plan view in plane X-Y of the IC wafer and magnifiedviews of a different group of circuit dies according to embodiments ofthe disclosure.

FIG. 4 provides a plan view in plane X-Y of a diced IC wafer andmagnified views of three circuit dies according to embodiments of thedisclosure.

FIG. 5 provides a cross-sectional view in plane X-Z of a plurality oflayers in a circuit die according to embodiments of the disclosure.

FIG. 6 provides a schematic view of an illustrative environment forimplementing methods according to embodiments of the disclosure.

FIG. 7 provides an illustrative flow diagram of methods according toembodiments of the disclosure.

FIG. 8 provides an illustrative flow diagram of a method formanufacturing IC structures according to embodiments of the disclosure.

FIG. 9 provides an illustrative flow diagram of a method for identifyingcircuit dies according to embodiments of the disclosure.

It is noted that the drawings of the invention are not to scale. Thedrawings are intended to depict only typical aspects of the invention,and therefore should not be considered as limiting the scope of theinvention. In the drawings, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION

Referring to FIG. 1, embodiments of the disclosure provide an integratedcircuit (IC) wafer 100 structured for the identifying of individualcircuit dies after the dicing of IC wafer 100. Technical challengesassociated with the manufacture of IC product units include the tracingof functional failing products (i.e., products which operate in a mannerother than intended) to specific regions of an IC wafer from which theproducts were manufactured. Functional failing products may include,e.g., defective chips and/or chips with functional failures.Conventional testing may be limited to evaluating the characteristics ofthe entire wafer prior to dicing, or examination of particular unitsafter manufacture, without any ability to associate an end product orbatch of products with a particular portion of the original wafer. Toprovide a more comprehensive model of quality management for IC productunits, embodiments of IC wafer 100 discussed herein may allow usersand/or manufacturers to identify a particular region of IC wafer 100where individual dies, products, etc., originated before dicingoccurred.

As shown in FIG. 1, IC wafer 100 (depicted via plan view in plane X-Y)may include a body 102, e.g., one or more semiconductor materials,dielectric materials, conductive materials, manufactured to include thedevice architecture of several products. Body 102 more specifically mayinclude multiple vertically separated layers therein, with at least twoof those layers being separately identified herein as first and secondlayers (e.g., layers L1, L2 of FIG. 5). The various portions of IC wafer100 to be separated into distinct products or groups of products may beidentified as circuit dies 104 to be separated into individual units.Each circuit die 104 may be laterally separated from other circuit dies104 on IC wafer 100 by a set of scribe lines 106 indicating the specificlocations where body 102 of IC wafer 100 will be diced in subsequentprocessing. Scribe liens 106 may take the form of grooves formed withinIC wafer 100, and thus may be visible to an observer in some instances.As shown, scribe lines 106 may be arranged in the shape of a grid onbody 102, such that each circuit die 104 covers a uniform surface areaon body 102. Non-rectangular portions of body 102 may be positionedoutside scribe lines 106.

The various regions and components of IC wafer 100 may have distinctroles before and after IC wafer 100 is separated into individual circuitdies. IC wafer 100 may be configured for dicing via one or moremechanical instruments (e.g., dicing blades), and/or other currentlyknown or later developed instruments such as laser dicing tools, etc.Prior to dicing, portions of body 102 located outside of scribe lines106 may not include functional features of a product therein, andinstead may include one or more test structures configured to analyze ICwafer 100 before dicing occurs. Thus, any materials used for testing ofIC wafer 100 located outside scribe lines 106 may have no significantuse after dicing concludes. As also noted above, each circuit die 104may also include sets of metal wires, vias, device components,dielectric materials, etc., therein, though such components are omittedfrom the depiction of IC wafer 100 in FIG. 1 solely for clarity ofillustration. Such components in each circuit die 104 are conventionallystructured only to yield the structural and operational features of eachdevice formed from IC wafer 100.

Turning now to FIG. 2, IC wafer 100 is shown with magnified views ofthree circuit dies 104 (identified separately as 104A, 104B, 104C) toillustrate features of IC wafer 100 in various embodiments. Each circuitdie 104 may include, e.g., one or more reference features 110 positionedin a first layer of a respective circuit die 104. As shown in eachmagnified view of circuit dies 104A, 104B, 104C, reference features 110may be equidistant from one of a respective set of scribe lines 106 foreach circuit die 104. To illustrate the equidistant separation eachreference feature 110 and each corresponding scribe line 106, aseparation distance E illustrates the same positional difference betweeneach reference feature 100 and each scribe line 106. Reference feature110 may be composed of any material capable of being structurallyidentified from the remainder of circuit die 104 and/or componentstherein. For example, reference feature 110 may include one or morelight-reflecting materials capable of detection within the structure ofcircuit die 104 before or after dicing occurs.

In various embodiments, reference feature(s) 110 may be composed of ametal wire, an insulative material (e.g., one or more photolithographicmasks), and/or other components distinct from other materials includedwithin circuit die 104. Furthermore, reference features 110 may bedistinct and/or other structurally disconnected from other portions ofcircuit die 104 for providing the operational structure and/or featuresof a particular product, despite being formed within a functional regionof one circuit die 104. Two reference features 110 are shown in eachcircuit die 104 for the sake of example, and it is understood that anydesired number of reference features 110 may be formed therein.Reference features 110 may exhibit an identical appearance in eachcircuit die 104, regardless of which individual circuit die (e.g.,circuit die 104A, 104B, 104C, etc.) is under analysis. Referencefeature(s) 110 may be positioned below an uppermost terminal layer ofcircuit die 104, and thus each reference feature 110 is depicted withphantom lines in each magnified view of FIG. 2.

Additional structures may be configured to identify the location of eachcircuit die 104 on IC wafer 100. Reference features 110 are shown tohave the same position in each circuit die 104. To provide an embeddedform of identification, each circuit die 104 may include one or moreidentification features 112 positioned in a second (i.e., different)layer as compared to the layer where reference features 110 appear. Twoidentification features 112 are shown in each circuit die 104 for thesake of example, and it is understood that any desired number ofidentification features 112 may be formed therein. To emphasize thelocation of identification feature(s) 112 as being in a different layerfrom reference feature(s) 110, identification features 112 areillustrated with different cross-hatching in circuit dies 104A, 104B,104C. Identification feature(s) 112 may each be formed from the same orsimilar material as reference feature(s) 110, e.g., a metal wire,insulator (e.g., one or more masking materials), reflective films,and/or other components capable of being distinguished from othermaterials in each circuit die 104.

The position of identification feature(s) 112 in embodiments of thedisclosure varies across each circuit die 104, thereby causingidentification feature(s) 112 to be different in each circuit die 104.The varying position of identification feature(s) 112 in each circuitdie 104 can be expressed in terms of an offset vector from referencefeature(s) 110, due to the uniform location of reference feature(s) 110in each circuit die 104. The offset vector may be expressed as a vectoror vector sum indicating the positional difference between two locations(i.e., the location of reference feature(s) 110) and the location ofidentification feature(s) 112). Magnified circuit dies 104A, 104B, 104Cillustrate how identification feature(s) 112 may distinguish betweenindividual circuit dies 104A, 104B, 104C. The offset vector foridentification feature(s) 112 may be expressed in terms of its magnitudeand direction. The magnitude may correspond to an amount of separationbetween identification feature(s) 112 and corresponding referencefeature(s) 110. The direction may correspond to one of several possiblepaths of separation between feature(s) 110, 112, e.g., latitudinaland/or longitudinal directions. In the example of FIG. 2, the offsetvector for each set of identification feature(s) 112 may be expressed asthe sum of a latitudinal offset between one reference feature 110 andone identification feature 112, and a longitudinal offset between theother reference feature 110 and other identification feature 112.Beginning with circuit die 104A, longitudinal-oriented identificationfeature 112 may be laterally separated from longitudinal-orientedreference feature 110 by a distance vector R (e.g., 100 micrometers(μm)) along the X-axis. Circuit die 104A may also includelatitudinal-oriented identification feature 112 separated fromlatitudinal-oriented reference feature 110 by a distance vector S (e.g.,100 micrometers (μm)) along Y-axis. Thus, the offset vector betweenidentification features 112 and reference features 110 of circuit die104 may be expressed as the sum of distance vectors R and S. In thiscase, the offset vector for identification features 112 of circuit die104A may not account for any vertical separation between the differentlayers of IC wafer 100 where reference features 110 and identificationfeatures 112 appear.

The positional difference between identification feature 112 andreference feature 110 in each circuit die 104 may be unique to onecircuit die 104 of IC wafer 100. The summed offset vector (e.g.,latitudinal vector R plus longitudinal vector S) for features 110, 112in circuit die 104A may be specific to only circuit die 104A, regardlessof whether its components vector R or vector S appear individually inanother circuit die 104. For instance, in circuit die 104B, the offsetvector between identification and reference features 112, 110 may be thesum of vector 2R (e.g., twice vector R, or approximately 200 μm, alongX-axis) in the latitudinal direction, and vector S (e.g., approximately100 μm) along Y-axis in the longitudinal direction. In circuit die 104C,the offset vector between identification and reference features 112, 110may be the sum of vector R (approximately 100 μm) along X-axis in thelatitudinal direction and vector 2S (e.g., twice vector S, orapproximately 200 μm, along Y-axis) in the longitudinal direction. Theresulting vector may preserve the latitudinal or longitudinalorientation of its component vectors, e.g., by being expressed as aresultant vector having a corresponding angle relative to X or Y axis.

Using circuit die 104C as an example, the offset vector foridentification features 112 may be converted from vectors R and 2S intoa single vector having a magnitude of approximately 220 μm and an angleof approximately 63 degrees relative to X-axis, via Euclidean geometry.In other cases, the offset vectors may be computed and expressed interms of their component vectors, rather than a resultant vector.Although circuit dies 104A and 104B share a longitudinal component(vector S) in their respective offset vectors, the total offset vectoris different in each circuit die. Similarly, circuit dies 104A, 104Calso have distinct offset vectors despite sharing a latitudinalcomponent (vector R) in their respective offset vectors.

Turning to FIG. 3, embodiments of IC wafer 100 can be structured suchthat differences in the offset vector for each circuit die 104 follow aspecific pattern. That is, identification features 112 in successivecircuit dies 104 along one axis may be structured to follow a coordinatesystem. To illustrate this feature, another circuit die 104D ismagnified together with circuit dies 104A, 104B. As shown, each circuitdie 104A, 104B, 104D is positioned along a shared axis in thelongitudinal direction. Thus, the offset vector between features 110,112 in each circuit die 104A, 104B, 104D may include a same longitudinalcomponent (i.e., vector S in the Y direction) but different latitudinalcomponents (i.e., vectors R, 2R, 3R for regions 104A, 104B, 104D,respectively). In this case, each latitudinal vector may increase by apredetermined multiple (e.g., approximately 100 μm) at each successivecircuit die along the shared axis. Thus, according to this example, theoffset vector for features 110, 112 in circuit die 104B may have twicethe latitudinal offset distance as the offset vector for features 110,112 in circuit die 104A. In the same example, the offset vector forfeatures 110, 112 in circuit die 104D may have three times thelatitudinal offset distance as the offset vector for features 110, 112,in circuit die 104A. The amount of change thus may be the same for eachsuccessive circuit die 104 in IC wafer 100 along a shared latitudinal orlongitudinal axis.

FIG. 4 illustrates how features 110, 112 may identify the initiallocation of a particular structure on IC wafer 100 (FIGS. 1-3), evenafter IC wafer 100 has been diced into individual pieces. FIG. 4 shows aplurality of circuit dies 204, each of which may have been previouslydiced from a single IC wafer (e.g., IC wafer 100 of FIGS. 1-3). Thevarious dies 204 may then be delivered to customers, third partyfabricators, etc. In conventional settings, it may be impossible todetermine the original location of a particular circuit die 204 on itscorresponding IC wafer 100. In embodiments of the disclosure, however,the various circuit dies 204 include the same structure of each circuitdie 104 (FIGS. 1-3) of IC wafer 100. Thus, it is possible to select onecircuit die 204 for analysis and inspect the location of referencefeatures 110 and identification features 112 in each circuit die.Circuit die 204A, for example, can be matched with circuit die 104A(FIGS. 2-3) by identifying the offset vector as being the sum of vectorR in the latitudinal direction and vector S in the longitudinaldirection. Circuit die 204B similarly can be matched with circuit die104B (FIGS. 2-3) by calculating vectors 2R and S therein. Circuit die204D can also be matched with circuit die 104D (FIG. 3) by calculatingvectors 3R and S therein. As noted elsewhere herein, the offset vectorbetween features 110, 112 may correspond to only one circuit die 104 ofa particular IC wafer 100. In the case where a particular circuit die204 is a functional failing device, it is possible to identify a portionof IC wafer 100 where the functional failure originated duringfabrication. During implementation, a user and/or other recipient ofcircuit dies 204 may provide a functional failing circuit die 204 to theoriginal manufacturer of IC wafer 100. The method then allows eachfailing circuit die 204 to be traced back to the portion of IC wafer 100where it was originally created. The manufacturer may then adjust one ormore tools associated with the portion of IC wafer 100 where circuitdie(s) 204 with functional failures originated.

Turning now to FIG. 5, a cross-sectional view of one circuit die 104 orcircuit die 204 is shown to better illustrate the location of referencefeatures 110 and identification features 112. As a result of dicingalong scribe lines 106, the portions of circuit die 104 depicted in FIG.5 may also be present in corresponding circuit dies 204. One scribe line106 is shown by example in FIG. 5 to illustrate its location in ICwafer(s) 100 (FIGS. 1-3), but it is understood that scribe lines 106will not appear on circuit dies 204 that have already been diced from ICwafer 100. Each circuit die 104 and/or circuit die 204 may include,e.g., a plurality of metal wires 304, each of which can be composed ofany currently known or later-developed electrically conductive materialincluding, e.g., copper (Cu), aluminum (Al), silver (Ag), gold (Au),combinations thereof, etc. Metal wires 304 can be formed and positionedwithin a layer of electrically insulative or semiconductive material(e.g., a region of semiconductor material or an electrically insulatingdielectric material), such that metal wires 304 transmit electricitybetween other electrically conductive structures in contact therewith.Metal wires 304 positioned within a lowermost terminal metal level M1can extend in a particular direction (e.g., along axis X). Metal wires304 positioned within an uppermost terminal metal level MN can similarlyextend along axis X in the same direction as metal wire(s) 304 inlowermost terminal metal level M1, or a different direction. Lowermostterminal metal level M1 and uppermost terminal metal level MN can bevertically separated from each other (e.g., along axis “Z” shown in FIG.5), either as directly adjacent metal levels or with intervening metaland insulator levels positioned therebetween.

Metal wires 304 within different metal levels (e.g., lowermost terminalmetal level M1 and uppermost terminal metal level MN) can beelectrically connected to each other with vias 306 each extendingvertically between lowermost terminal metal level M1 and uppermostterminal metal level MN. Vias 306 can be composed of the sameelectrically conductive material(s) as each metal wire 304, or can becomposed of one or more different conductive materials. Each via 306, inan embodiment, can comprise any standard conductive metal (for example,copper) with a lining material (not shown) thereon, such as tantalumnitride.

Lowermost and uppermost terminal metal levels M1, MN can be separatedfrom one another by one or more intervening metal levels 308 (eachlabeled, e.g., as M2, M3, M4, M5, MN−1). As suggested by the notationsMN and M1, the number of metal levels can vary depending on the chosenimplementation and any requirements for back end of line (BEOL)processing. Circuit die 104 and/or circuit die 204 can also includeinterlayer dielectrics 310 positioned between each intervening metallevel 308. Each interlayer dielectric 310 can include one or moreelectrically insulative substances including, without limitation:silicon nitride (Si₃N₄), silicon oxide (SiO₂), fluorinated SiO₂ (FSG),hydrogenated silicon oxycarbide (SiCOH), porous SiCOH,boro-phospho-silicate glass (BPSG), silsesquioxanes, carbon (C) dopedoxides (i.e., organosilicates) that include atoms of silicon (Si),carbon (C), oxygen (O), and/or hydrogen (H), thermosetting polyaryleneethers, SiLK (a polyarylene ether available from Dow ChemicalCorporation), a spin-on silicon-carbon containing polymer materialavailable from JSR Corporation, other low dielectric constant (<3.9)material, or layers thereof. In some embodiments, it is also understoodthat different interlayer dielectrics 310 can be composed of differentmaterials with correspondingly different dielectric constants. In oneembodiment, one or more vias 308 can extend from one metal level to anadjacent metal level, such that metal wire(s) 304 in lowermost terminalmetal level M1 can be electrically connected to metal wire(s) 304 inuppermost terminal metal level MN of circuit die 104 or circuit die 204.

In the cross-sectional view of circuit die 104 or circuit die 204, afirst layer L1 may be fabricated to include reference feature(s) 110located near a corresponding metal wire 308 in the same level (e.g.,metal level M4 of FIG. 5). Although metal level M4 is shown by exampleto be level where reference feature(s) 110 is formed within circuit die104 or circuit die 204, it is understood that reference feature(s) 110may be formed in any one of the various metal levels M1 through MN. Anyof the metal levels M1-MN may be separately identified as first layerL1, and may include reference feature(s) 110 therein. A second layer L2of circuit die 104 or circuit die 204 may include identificationfeature(s) 112, e.g., formed on interlayer dielectric 310 of the samelevel and proximal to metal wire(s) 304 in the same metal level. Asshown, second layer L2 with identification feature(s) 112 therein may beuppermost terminal metal level MN. One benefit to forming identificationfeature(s) 112 in uppermost terminal metal level MN may be an improvedability to detect the location of identification feature(s) 112 incircuit die 104 or circuit die 204. However, it is also understood thatsecond layer L2 may refer to any layer where identification feature(s)112 appear, e.g., any of the various metal layer M1 through MN in aparticular circuit die 104 or circuit die 204. To sense the position ofreference feature(s) 110 and/or identification feature(s) locatedbeneath other layers of circuit die 104, any currently known orlater-developed sensing instruments (e.g., electromagnetic sensors,thermal sensors, etc.) can be used to determine the location of specificunderlying materials.

Turning to FIG. 6, process methodologies according to the disclosure maybe implemented using an environment 400 having one or more computingdevices 402. Computing device 402 and example components thereof may beimplemented in various systems and methods according to embodiments ofthe present disclosure. As discussed herein, computing device 402 can bein communication with IC wafer 100 and/or circuit dies 204 according toembodiments. To this extent, computing device 402 can perform variousprocesses to identify a position on IC wafer 100 where circuit dies 204originate, after dicing occurs. Although one IC wafer 100 and oneplurality of circuit dies 204 are shown for the sake of example, it isunderstood that environment 400 may be configured to operate on and/orinteract with multiple IC wafers 100 or pluralities of circuit dies 204,sequentially and/or simultaneously.

Environment 400 shown to include computing device 402 including aprocessing unit (PU) 404 (e.g., one or more processors), a memory 406(e.g., a storage hierarchy), an input/output (I/O) component 408, an I/Odevice 410 (e.g., one or more I/O interfaces and/or devices), a storagesystem 412 and a communications pathway 414. In general, PU 404 executesprogram code, such as a wafer identification system 418 at leastpartially fixed in memory 406. While executing program code, PU 404 canprocess data, which can result in reading and/or writing transformeddata from/to memory 406 and/or I/O device 408 for further processing.Pathway 414 provides a communications link between each of thecomponents in computing device 402. I/O component 408 can comprise oneor more human I/O devices, which enable a human or system user tointeract with computing device 402 and/or one or more communicationsdevices to enable user(s) to communicate with computing device 402 usingany type of communications link. To this extent, wafer identificationsystem 418 can manage a set of interfaces (e.g., graphical userinterface(s), application program interface, etc.) that enable user(s)to interact with wafer identification system 418. Wafer identificationsystem 418 may include a group of modules 420 to perform variousfunctions as discussed herein. Further, wafer identification system 418can manage (e.g., store, retrieve, create, manipulate, organize,present, etc.) a set of identification data 430 using any solution.Environment 400 may also include, e.g., a manufacturing device 440 inthe form of one or more currently known or later developed tools forfabrication of IC wafer(s) 100, and/or a dicing system 450 configured todice IC wafer 100 into a plurality of circuit dies 206 (e.g., alongscribe lines 106 (FIGS. 1-3).

Computing device 402 can comprise one or more computing devices,including specific-purpose computing articles of manufacture (e.g.,computing devices) capable of executing program code, such as waferidentification system 418 installed thereon. As used herein, it isunderstood that “program code” means any collection of instructions, inany language, code or notation, that cause a computing device having aninformation processing capability to perform a particular functioneither directly or after any combination of the following: (a)conversion to another language, code or notation; (b) reproduction in adifferent material form; and/or (c) decompression. To this extent, waferidentification system 418 can be embodied as any combination of systemsoftware and/or application software.

Further, wafer identification system 418 can be implemented using a setof modules 420, e.g., a calculator, comparator, a determinator, etc. Inthis case, each module can enable computing device 402 to perform a setof tasks used by wafer identification system 418, and can be separatelydeveloped and/or implemented apart from other portions of waferidentification system 418. One or more modules can display (e.g., viagraphics, text, sounds, and/or combinations thereof) a particular userinterface on a display component such as a monitor. When fixed in memory406 of computing device 402 that includes PU 404, each module can bemodule a substantial portion of a component that implements thefunctionality. Regardless, it is understood that two or more components,modules and/or systems may share some/all of their respective hardwareand/or software. Further, it is understood that some of thefunctionality discussed herein may not be implemented or additionalfunctionality may be included as part of computing device 402.

As noted herein, wafer identification system 418 may include orotherwise have access to various forms of identification data 430.Identification data 430 may be included within memory 406 as shown inFIG. 6, and in addition or alternatively may be provided within storagesystem 412 and/or other components within environment 400 orcommunicatively connected thereto. An IC wafer map 432 of identificationdata 430 may provide a listing, graphical depiction, etc., of allcircuit dies 104 (FIGS. 1-3, 5) in one IC wafer 100. Identification data430 may also include, e.g., an offset index 434 correlating each circuitdie 104 with the corresponding offset vectors for reference feature(s)110 (FIGS. 1-5) and identification feature(s) 112 for each circuit die104 in IC wafer 100. As discussed elsewhere herein, identifying circuitdie(s) 204 as corresponding to circuit die(s) 104 in one IC wafer mayinclude measuring the offset vector of circuit die(s) 204 underanalysis. These measurements may be take the form of measured offset(s)436 in identification data 430.

When computing device 402 comprises multiple computing devices, eachcomputing device may have only a portion of wafer identification system418 (e.g., one or more modules) thereon. However, it is understood thatcomputing device 402 and wafer identification system 418 are onlyrepresentative of various possible equivalent computer systems that mayperform a process described herein. To this extent, in otherembodiments, the functionality provided by computing device 402 andwafer identification system 418 can be at least partially implemented byone or more computing devices that include any combination of generaland/or specific purpose hardware with or without program code. In eachembodiment, the hardware and program code, if included, can be createdusing standard engineering and programming techniques, respectively.

Regardless, when computing device 402 includes multiple computingdevices, the computing devices can communicate over any type ofcommunications link. Further, while performing a process describedherein, computing device 402 can communicate with one or more othercomputer systems using any type of communications link. In either case,the communications link can comprise any combination of various types ofwired and/or wireless links; comprise any combination of one or moretypes of networks; and/or use any combination of various types oftransmission techniques and protocols.

Referring concurrently to FIGS. 3-7, the disclosure includes variousmethodologies for manufacturing IC wafers 100 for identification, and/oridentifying portions of IC wafer 100 where circuit dies 204 originate.Viewed generally, processes according to the disclosure may includemethods for creating IC wafer 100 with identifying structures (e.g.,reference features 110 and identification features 112) therein forfuture analysis, and/or related methodologies for identifying theoriginal location of a circuit die 204 in IC wafer 100 after dicing hascompleted. At process P1, the disclosure may include fabricating wafer100 to include one or more reference features 110 in a first layer ofeach circuit die 104, and one or more identification features 112 in asecond layer of each circuit die 104. As noted elsewhere herein,reference feature(s) 110 may have the same separation distance fromcorresponding scribe lines 106 in each circuit die, while identificationfeature(s) 112 may have a different offset vector from referencefeature(s) 110 in each circuit die 104. In conventional settings,manufacturing device 440 may be configured to create a uniform productdesign for the functional elements in all circuit dies 104 of IC wafer100. As noted elsewhere herein, forming IC wafer 100 according to thedisclosure includes forming identification features 112 at differentlocations in each circuit die 104. To form identification features 112at a different location in each circuit die 104, modules 420 ofcomputing device 402 may automatically adjust the position whereidentification feature(s) 112 are formed in each circuit die, e.g., byadjusting the position of one or more masks, deposited metals, etc.,along a set pattern. Such patterns, e.g., increasing the separationdistance of identification feature(s) 112 from associated referencefeature(s) 110 in each circuit die 104 by a predetermined multiple,e.g., as shown in FIG. 3 and discussed elsewhere herein. Whereidentification feature(s) 112 are formed by deposition, the adjustingmay be applied to a deposition tool for creating one or more metals inIC wafer 100. In cases where identification feature(s) 112 are formed bycombinations of masking, etching, etc., modules 420 of computing device402 may adjust the position of such components to modify the location ofidentification feature(s) 112. In all other respects, the fabrication ofIC wafer 100 may proceed substantially in accordance with conventionalwafer fabrication techniques. Additional sub-processes of process P1 areshown in FIG. 8 and discussed elsewhere herein.

Upon completion of process P1, the method may conclude (“Done”) in caseswhere IC wafer 100 is diced in an independent process. In other cases,the flow may continue to process P2 of using dicing system 450 to diceIC wafer 100 into multiple circuit dies 204. The dicing of IC wafer 100may proceed substantially in accordance with conventional wafer dicing,despite the presence of reference features 110 and identificationfeatures 112 in each circuit die 104. More specifically, referencefeatures 110 and identification features 112 may not be located near oralong scribe lines 106, and thus will not affect the dicing of IC wafer100 into circuit dies 204.

Whether IC wafer 100 is diced into circuit dies 204 as part of a singleprocess for identifying circuit dies, or a preliminary operationindependent from identifying each circuit die, the disclosure mayinclude process P3 of identifying the original location of one or morecircuit dies 204 on IC wafer 100. Specific techniques, sub-processes,etc., for identifying the original location of circuit die(s) 204 on ICwafer 100 in process P3 are shown in further detail in FIG. 9 anddescribed elsewhere herein. Identifying the original location of eachcircuit die 204 on IC wafer 100 may include, for example, measuring theoffset vector for identification feature(s) 112 on each circuit die 204and comparing the measured value to offset index 434, and thendetermining the location based on which offset distance of index 434matches the measured value. The flow may then conclude (“Done”) for thecircuit dies 204 being identified.

Referring concurrently to FIGS. 3-6 and 8, an example group ofsub-processes for process P1 of fabricating a wafer with referencefeatures 110 and identification features 112 in circuit dies 104 isprovided. In a preliminary process P1-1, the disclosure may includedefining the various circuit dies 104 of IC wafer 100. Process P1-1 isshown in phantom to emphasize that this process may not be included inall instances of process P1 and/or may be executed by other entities.Process P1-1 may occur, e.g., prior to the fabrication of IC wafer 100by defining the location of scribe lines 106 in a design for IC wafer100 and circuit dies 204. Scribe lines 106 may also be formed directlyon IC wafer 100 after the fabrication of IC wafer 100 and prior todicing.

Regardless of how circuit dies 104 are defined, process P1-2 accordingto the disclosure may include forming first layer L1 (e.g., anypredetermined metal level such as one or more of metal levels M1-MN ofFIG. 5) with reference feature(s) 110 therein. As noted previously,reference feature(s) 110 may have a uniform separation distance fromcorresponding sets of scribe lines 106 in each circuit die 104 of ICwafer 100. Continued fabrication of IC wafer 100 can then proceed toprocess P1-3 of forming second layer L2 (e.g., any other predeterminedmetal level such as one or more of metal levels M1-MN of FIG. 5) withidentification feature(s) 112 therein.

After completing processes P1-2 and P1-3, continued fabrication of ICwafer 100 may optionally include fabricating all other layers wherefeatures 110, 112 do not appear. In alternative implementations, thevarious remaining layers may be formed before the layers designated asbeing first layer L1 and second layer L2, and/or between the forming offirst layer L1 and second layer L2. In still further embodiments (e.g.,forming second layer L2 as lowermost terminal metal level M1), secondlayer L2 may be formed before first layer L1. In any case, the methodmay include ending the fabrication of IC layer 100 in process P1-5,e.g., after forming the functional components and features 110, 112which constitute each circuit die 104 of IC wafer 100. Upon completingthe fabrication of IC wafer 100, modules 420 of wafer identificationsystem 418 can store IC wafer map(s) 432 for future use asidentification data 430. The generating and/or storing of IC wafermap(s) 432 for subsequent use may also occur as part of one of processesP1-1 through P1-4, or a separate operation. In cases where anotherentity is responsible for identifying circuit dies 204, the flow mayconclude (“Done”) after process P1-5. In other situations, the methodmay continue to process P2 of dicing IC wafer 100 into circuit dies 204to be identified.

Referring concurrently to FIGS. 3-6 and 9, embodiments of the disclosuremay include one or more sub-processes for identifying the originallocation of each circuit die 204 on IC wafer 100. In process P3-1, forexample, one or more circuit dies 204 (containing, e.g., one or morefunctional failures such as manufacturing defects or anomalies) may beselected for analysis based on examination and/or testing. At processP3-2, a user may examine circuit die(s) 204 under analysis (e.g.,manually or automatically with the assistance of software, tools, etc.)to measure the offset vector between identification feature(s) 112 andreference feature(s) 110 located on circuit die(s) 204 under analysis.According to an example, an electromagnetic imaging tool may detect theposition of one reference feature 110 and one identification feature 112extending in parallel with the reference feature 110. The imaging toolmay then, e.g., with the aid of modules 420, measure, calculate, etc.,the separation distance between identification feature 112 and referencefeature 110 along one axis. The imaging tool may subsequently, orconcurrently, detect the position of other reference features 110 withdifferent orientations and identification features 112 which share thedifferent orientation, to calculate a separation distance between suchfeatures 110, 112 along a different axis. The various differences inposition for each pair of features 110, 112 can then be combined witheach other to yield an offset vector for one circuit die 204 underanalysis. As noted elsewhere herein, the offset vector may indicate aseparation distance between identification feature(s) 112 and referencefeature(s) 110, including both an amount of separation and a separationorientation (e.g., latitudinal or longitudinal separation) betweenfeatures 110, 112 on circuit die(s) 204. The measured offset vector(s)for each circuit die 204 may be stored, e.g., in memory 406, as measuredoffset(s) 436 in identification data 430.

Further processes may include using measured offset(s) 436 and otherforms of identification data 430 to determine a particular circuit die104 from which circuit die 204 was created. At process P3-3, the methodmay include comparing measured offset(s) 436 for circuit dies 204 withknown offset vectors in offset index 434. More specifically, comparatormodules 420 of wafer identification system 418 can match one or moremeasured offset(s) 436 with their corresponding values in offset index434. To account for errors in measurement and/or computation, acalculator of modules 420 may apply one or more tolerance thresholds inthe comparison and/or find a best fit match between measured offset(s)436 and one or more offset vectors in offset index 434. In any case,process P3-3 may pair each measured offset 436 to a corresponding offsetvector in offset index 434, e.g., by identifying offset vectors within amargin of error for the measured offsets 436 for a particular IC die 204under analysis. Continuing to process P4-4, the method may includeidentifying the original location of each circuit die 204 on IC wafer100. According to an embodiment, IC wafer map(s) 432 of identificationdata 430 may include corresponding offset vectors for circuit die 104 ofIC wafer 100.

This formatting may allow each measured offset 436 previously matchedwith an offset vector in offset index 434 to automatically be matchedwith a particular circuit die 104. At this point, modules 420 cancommunicate (e.g., via I/O device 410) which circuit die(s) 104 of ICwafer 100 originated circuit die(s) 204. In cases where a particularanomaly detected on one circuit die 204, a portion of IC wafer 100 wherecircuit die 204 originated can be identified as originating thefunctional failure of a device. The manufacturing tools, design, and/orother components associated with such portions of circuit die 204 maythen be modified to correct errors, compensate for unanticipatedoperating characteristics, etc. Subsequently, the process may end(“Done”) with respect to the particular circuit die(s) 204 underanalysis. It is again noted that processes P1 and P3 may each take theform of an independent methodology, process, etc., to be implemented byindependent entities, or may be implemented together with process P2 asportions of a single, unified process.

The method as described above is used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

These computer program instructions may also be stored in a computerreadable medium that may direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowcharts and block diagrams in the Figures illustrate the layout,functionality, and operation of possible implementations of systems,methods and computer program products according to various embodimentsof the present invention. In this regard, each block in the flowchart orblock diagrams may represent a module, segment, or portion of code,which comprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, may be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. “Optional” or “optionally” means thatthe subsequently described event or circumstance may or may not occur,and that the description includes instances where the event occurs andinstances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately,” and “substantially” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged, such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.“Approximately” as applied to a particular value of a range applies toboth values, and unless otherwise dependent on the precision of theinstrument measuring the value, may indicate +/−10% of the statedvalue(s).

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. An integrated circuit (IC) structure having a plurality of circuit dies each bounded by a set of scribe lines, the IC structure comprising: a plurality of reference features each respectively positioned in a first layer of one of the plurality of circuit dies, wherein the plurality of reference features of the one of the plurality of circuit dies include a first reference line extending along a first axis of the IC structure and a second reference line extending along a second axis orthogonal to the first axis of the IC structure, and a plurality of identification features each positioned in a second, different layer of the one of the plurality of circuit dies, the plurality of identification features of the one of the plurality of circuit dies having an offset vector indicative of a positional difference between the identification features for the circuit dies and the reference features for the one of the plurality of circuit dies, wherein one or both of the first reference line and the second reference line of each one of the plurality of circuit dies is equidistant from a respective one of the set of scribe lines for each circuit die of the plurality of circuit dies.
 2. The IC structure of claim 1, wherein the plurality of reference features and the plurality of identification features of each circuit die are included within a functional region of the respective circuit die.
 3. The IC structure of claim 1, wherein the offset vector for each circuit die of the IC structure along a shared axis has a same offset orientation.
 4. The IC structure of claim 1, wherein one or both of the plurality of reference features and the plurality of identification features comprise one of a metal wire or an insulator.
 5. The IC structure of claim 1, wherein an aligned row of circuit dies in the IC structure includes a first circuit die having a first offset vector, and a second circuit die having a second offset vector, wherein an offset distance for the identification features in the second circuit die is twice the offset distance for the identification features in the first circuit die.
 6. The IC structure of claim 5, wherein the aligned row of circuit dies in the IC structure further includes a third circuit die having a third offset vector, wherein an offset distance for the identification features in the third circuit die is three times the offset distance for the identification features in the first circuit die.
 7. The IC structure of claim 1, wherein the plurality of identification features include two identification lines, each parallel to a respective one of the first and the second reference lines of the plurality of reference features. 